Utilities that provide electric, gas, water and/or telephone service usually do so via a network of underground pipes and/or cables, hereinafter collectively referred to as "underground utility conveyances." To alert the public of the presence of such underground utility conveyances, most utilities usually mark the right-of-way of such conveyances with spaced-apart above-ground warning signs. Despite such warning signs, damage to underground utility conveyances still occurs, mostly as a result of inadvertent excavation by a contractor who is usually unaware of the presence of the underground utility conveyance.
Damage to an underground utility conveyance by inadvertent excavation has disastrous consequences. Depending on the damage inflicted, repairs to the underground utility conveyance can be very expensive. Further, while the underground utility conveyance is being repaired, service is usually disrupted to utility customers, resulting in lost revenues to the utility. Moreover, for underground utility conveyances that carry natural gas or other hazardous substances, inadvertent excavation may not only lead to pecuniary loss but personal injury as well.
Thus, there is a need for an improved technique for warning of potential harm to an underground utility conveyance by inadvertent excavation.